The present invention relates to an ion deposition web-fed print engine having novel and improved features facilitating operation and servicing of the print engine.
Ion deposition printers conventionally transpose or transform computer-generated signals, such as word processing signals, for image printing on a print medium, for example, paper. More particularly, an ion deposition print engine typically includes an image cylinder mounted in opposition to an impression cylinder with the print medium, i.e., a web of paper, passing between the image and impression cylinders. The image cylinder includes a dielectric layer which receives an electrostatic image from an ion cartridge. The cartridge is driven electronically from the computer or word processing system. The electrostatic image imposed on the image cylinder is contacted with toner from a supply. At the nip between the image and impression cylinders, the toner is transferred to the print medium, i.e., the paper, in the identical form of the electrostatic image on the image cylinder and fused to the medium. Further rotation of the image cylinder causes it to pass a multi-component cleaning station which physically removes solid particulate matter. The image cylinder finally passes under a discharge head which removes any residual electrostatic charge on the image cylinder surface, whereby a fresh electrostatic image may be placed on the dielectric layer by the ion cartridge. The process is then repeated with the same or different images.
The location and arrangement of the various parts of prior ion deposition print engines have, to a substantial extent, complicated servicing the engine. For example, frequently it has been difficult to expose the internal parts of the engine to maintenance personnel and procedures. Replacing component parts, cleaning various areas of the engine and replacing the paper web are typically difficult to achieve. There is also the necessity to maintain substantial pressure between the image and impression cylinders during operation to effect printing. Accordingly, servicing ion deposition print engines has remained a significant problem.
Additionally, problems in paper web handling have also been encountered during service and maintenance procedures. For example, during such procedures, the paper would oftentimes go slack through the print engine when the impression cylinder is disengaged relative to the image cylinder. Once maintenance procedures were completed, the slack paper may lose registration. Further, the design of prior print engines of this type may be damaged by debris caught in the web and transported into the nip between the image and impression cylinders. Additionally, accommodation for splices in paper is frequently difficult to achieve. For example, debris or splice sensors are often disposed in the engine. Most prior ion deposition print engines employ a heavy mass of parts which inhibit quick disengagement in the event debris and splices are sensed. Undesirably, this heavy mass of parts must also be moved for maintenance purposes. Further, substantial pressure is required between the image cylinder and impression cylinder and this must be maintained balanced across the entirety of the width of the print area during printing.
Additionally, many prior print engines of this type are limited in the width of paper which can be printed. That is, in most print engines, the image cylinder and impression cylinder are not movable and can handle only a single predetermined maximum width of paper.
In accordance with the present invention, there is provided a novel and improved ion deposition web-fed print engine which vastly facilitates servicing of the print engine, enables printing on substantially wider widths of paper webs while maintaining the necessary force to achieve proper toner transfer, enables print at any lateral position across the paper webs by providing for movement of the image cylinder and impression cylinder in the cross-paper width direction, preferably a synchronized movement, enables servicing without removal or slackening of the paper web, reduces the number of movable parts necessary to both engage and disengage the paper between the image cylinder and impression cylinder and, hence, the mass of parts required for quick disengagement in the event of debris entering or the sensing of a splice between the image and impression cylinders, affords greater control and uniformity of the forces acting between the image cylinder and impression cylinder and affords various other advantages in construction, operation and use, and particularly during servicing.
Particularly, the present invention provides a first, fixed or stationary, base frame having an impression cylinder carried between end plates of the frame for carrying the print medium in web form. The impression cylinder is carried for transverse movement relative to the base frame, i.e., movement in a direction parallel to the axis of the impression cylinder.
A second frame is carried by the first frame for pivotal movement about a transversely extending axis, between print engine open and closed positions, i.e., between service and operating positions, respectively. A third frame is carried by the second frame for pivotal movement with the second frame and also for movement in a transverse direction relative to the first and second frames, i.e., a direction parallel to the axes of rotation of the image and impression cylinders. The third frame carries a print unit, including the image cylinder. Thus, the image cylinder is movable with the second frame between the print engine closed and open positions and, with the third frame, in a transverse direction. The transverse movement of both the impression cylinder and the image cylinder is accomplished by a series of lead screws connected between the end plates of the first frame. Thus, joint movement of the image cylinder and the impression cylinder is accomplished to ensure registration and printing in the proper area at any position across the entire width of the paper, should the width of the paper be larger than the axial extent of the image cylinder and impression cylinder.
The image cylinder is also carried by the third frame for linear movement in a direction toward and away from the impression cylinder. The image cylinder is mounted on linear bearings and maintained in a nip open position relative to the impression cylinder when the second frame is pivoted to the print engine closed position. Consequently, a small space at the nip is provided between the image cylinder and impression cylinder prior to operating the print engine. Fluid-actuated cylinders cooperate between the image cylinder and the third frame to displace the image cylinder toward and into engagement with the impression cylinder to apply substantial forces to the paper passing through the nip. Coil springs are used to return the image cylinder to the nip open position when the hydraulic pressure is removed.
In a preferred embodiment according to the present invention, there is provided a print engine comprising a first fixed frame, an impression cylinder carried by the fixed frame for carrying a medium for receiving print and defining an axis extending in a transverse direction, a second frame carried by the first frame for pivotal movement about an axis extending in the transverse direction between print engine open and closed positions and a third frame carried by the second frame for pivotal movement therewith and for movement in the transverse direction. Means are provided for moving the third frame relative to the first and second frames in the transverse direction. A print unit is carried by the third frame for pivotal and transverse movement therewith and for movement relative thereto in a direction generally normal to the transverse direction, the print unit including an image cylinder carried for movement therewith in the transverse and normal directions, the image cylinder defining an open nip with the impression cylinder when the second frame lies in the print engine closed position, with additional means for moving the image cylinder in the generally normal direction to close the nip between the image cylinder and the impression cylinder when the second frame lies in the print engine closed position.
In a further preferred embodiment according to the present invention, there is provided a print engine, comprising a first fixed frame, an impression cylinder carried by the first frame for carrying a medium for receiving print and defining an axis extending in a transverse direction, a frame carried for pivotal movement on the first frame, an image cylinder carried by the pivotal frame for pivotal movement therewith between a print engine open position wherein the image cylinder is spaced from the impression cylinder to enable access within the print engine and a print engine closed position wherein the image cylinder lies closely adjacent to but spaced from the impression cylinder to define an open nip with the impression cylinder. Means are carried by the pivotal frame for moving the image cylinder toward the impression cylinder to close the nip therebetween when the pivotal frame lies in the print engine closed position.
In a further preferred embodiment according to the present invention, there is provided a print engine comprising a first fixed frame, a rotatable impression cylinder carried by the fixed frame for carrying a medium for receiving print and defining a rotational axis extending in a transverse direction, a second frame carried by the first frame for pivotal movement about an axis extending in a transverse direction between print engine open and closed positions and a third frame carried by the second frame for pivotal movement therewith and for movement in the transverse direction. An element cooperable between the third frame and at least one of the first and second frames is provided for moving the third frame relative to at least one of the first and second frames in the transverse direction and a print unit is carried by the third frame for pivotal and transverse movement therewith and having an image cylinder defining a nip with the impression cylinder when the second frame lies in the print engine closed position.
In a further preferred embodiment according to the present invention, there is provided a print engine comprising a first fixed frame, a rotatable impression cylinder carried by the fixed frame for carrying a medium for receiving print and defining a first rotational axis extending in a transverse direction, a second frame carried by the first frame for pivotal movement about a second axis extending in a transverse direction and between print engine open and closed positions, a print unit carried by the second frame for pivotal movement therewith and including an image cylinder carried thereby for rotational movement about a third rotational axis extending in a transverse direction and spaced from the first and second rotational axes and a driving element carried by the first frame and a driven element carried by the second frame. Means are provided for interconnecting the driving element and the driven element for rotating the image cylinder about the third axis, the driving element and the driven element being located on the first frame and the second frame, respectively, with the interconnecting means maintaining a driving relation therebetween when the second frame lies in each print engine open and closed positions.
In a further preferred embodiment according to the present invention, there is provided a print engine comprising a first fixed frame, a rotatable impression cylinder carried by the fixed frame for carrying a medium for receiving print and defining a first rotational roller axis extending in a transverse direction, a second frame carried by the first frame for pivotal movement about a second axis extending in a transverse direction and between print engine open and closed positions, and a third frame carried by the second frame for pivotal movement therewith and for movement in a transverse direction. An image cylinder is carried by the third frame for pivotal movement therewith and for linear movement relative thereto in a direction generally parallel to the transverse direction, the image cylinder being rotatable about a third rotational axis extending in the transverse direction. Means rotatably coincident with the second axis are provided for driving the image cylinder about the third axis and means are carried by the first frame and engageable with the third frame for moving the third frame in the transverse direction.
Accordingly, it is a primary object of the present invention to provide a novel and improved ion deposition print engine having constructional features enabling significantly increased accessibility for servicing the engine with fewer parts to be moved for access and service, as well as other advantages, in comparison with prior ion deposition print engines.
These and further objects and advantages of the present invention will become more apparent upon reference to the following specification, appended claims and drawings.